JPH069007B2 - NC data creation method for compound curved surface - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of use> The present invention relates to a method for creating NC data of a compound curved surface, and in particular, specifies a cutting path pattern for each curved surface constituting the compound curved surface, and specifies the specified cutting path. The present invention relates to a compound curved surface NC data creation method capable of cutting by moving a tool along a cutting path corresponding to a pattern.

<Prior Art> Processing of a complex curved surface formed by synthesizing two or more three-dimensional curved surfaces may be required. FIG. 7 is a side view (FIG. 7 (A)) and a plan view (FIG. 7 (B)) of a composite curved surface formed by combining two three-dimensional curved surfaces (hereinafter simply referred to as curved surfaces) 1 and 2. The curved surface 1 has a truncated cone shape, the curved surface 2 has a semi-cylindrical shape, and has a boundary line 3. In order to machine such a complex curved surface, one cutting path pattern is conventionally designated for the entire compound curved surface, points on an actual cutting path are discretely obtained based on the cutting path pattern, and each point is continuously tooled. The NC data is created so as to trace, and the composite curved surface is processed based on the NC data.

For example, in the example shown in FIG. 7, the cutting passage pattern is a group of straight lines that are radially incremented from the center P _C (see FIG. 7B) by an angle a °, and each straight line has a point P of radius r.
_{i (i} = 1,2, ···) is the line segment from the up cutting boundary point _{Q i,} the NC data for the compound curves machining from approach for NC data points _{P 1} to point _{P 1} until _{Q 1} as the pick feed for NC data points _{P 2} to the cutting NC data points _{P 2} of the NC data ........... for pick feed to the cutting NC data points _{P 3} up to _{Q 2} Is generated.

<Problems to be Solved by the Invention> When NC data is created by designating only one cutting path pattern per compound curved surface and the compound curved surface is processed by the created NC data, the generated compound data is generated. There is a problem that an unnatural striped pattern may occur on the curved surface, and the curved surface cannot be finished beautifully.

In view of the above, the object of the present invention is to provide a composite curved surface N that allows a tool to be moved along a cutting path pattern that matches the shape of each curved surface that forms the complex curved surface to finish the machined surface beautifully.
It is to provide a C data creation method.

<Means for Solving Problems> FIG. 1 is a schematic explanatory view of the present invention.

Reference numeral 10 is a complex curved surface, and 11 and 12 are curved surfaces constituting the complex curved surface. The curved surface 11 has a truncated cone and the curved surface 12 has a semi-cylindrical shape. Reference numeral 13 is a boundary line between the curved surfaces 11 and 12.

The radial straight line group 21 is the cutting passage pattern of the curved surface 11, and the parallel straight line group 22 is the cutting passage pattern of the curved surface 12.

<Operation> Data for specifying the respective curved surfaces 11 and 12 constituting the complex curved surface 10 and the cutting passage patterns 21 and 22 of each curved surface are input, and the cutting start point P _i of one curved surface 11 is set to the curved surface. Points are obtained discretely along one cutting path pattern 21 that has been formed up to the boundary point R _i with another curved surface 12, and then along one cutting path pattern 22 specified for the other curved surface 12. The points on the other curved surface are discretely obtained up to the cutting direction boundary point S _i , and the points are continuously traced (P _i → R _i → S _i ) to create NC data for generating a compound curved surface.

<Embodiment> FIG. 2 is a block diagram of an automatic programming device for implementing the method of the present invention. In the figure, 101 is a data input keyboard, 102 is a processor, 103 is a ROM for storing a control program, 104 is a RAM, 105 is a working memory, 106 is the generated curved surface data of the complex curved surface, and an NC program for curved surface processing. A curved surface storage memory for storing data, 107 a curved surface data of the generated complex curved surface or NC program data for curved surface processing is a paper tape,
An output device for outputting to an external storage medium 108 such as a magnetic tape, 109 is an address bus, and 110 is a data bus.

Hereinafter, a method for creating NC data of a compound curved surface according to the present invention will be described with reference to the flowchart of FIG. It is assumed that the NC data for composite curved surface processing shown in FIG. 1 is created.

(a) First, data for specifying the first curved surface 11 and the second curved surface 12 constituting the complex curved surface 10 (see FIG. 1) are input from the keyboard 101, respectively. The data for identifying the curved surface is an operation curve, a reference curve, etc., and is well known, so a detailed description thereof will be omitted. The curved surface 11 is defined as SS2, and the curved surface 12 is defined as SS1.

(b) Next, from the keyboard 101, for each of the curved surfaces 11 and 12 constituting the compound curved surface 10, input data for specifying a number of cross sections perpendicular to the XY plane for cutting the curved surfaces,
It is stored in the RAM 104.

That is, for each curved surface, one intersection line on the XY plane and a rule and a cutting range for identifying a large number of intersection lines on the XY plane based on the intersection line are input.

For example, when each cross section is parallel to each other and perpendicular to the XY plane, and the interval between the adjacent cross sections is constant, the intersection line CVi (i = 1, 2, 1) between each cross section and the XY plane. ，
3, ...) is as shown in FIG. Therefore, in such a case, the data for identifying the first intersection line CV1, the respective axis components (V _X , V _Y ) of the vector, and the distance d ₁ between the two intersection lines adjacent to each other are input.

The cutting path pattern is specified by the intersection line data and the distance d _1, and the cutting range is specified by the length and vector of the intersection line. Further, in FIG. 4, the direction of arrow A is the cutting direction, and the direction of B is
The arrow direction is called the feed direction.

And, in fact, the following command CV1 = ······; GROUP, 1, V X, V Y, d 1, i; become. Here, GROUP, 1 indicates a cutting path pattern of the type shown in FIG. 4 (A), and the numerical value i indicates the i-th curved surface SSi.

When each cross section is perpendicular to the XY plane and the angle between adjacent cross sections is constant, the line of intersection CVi between each cross section and the XY plane (i = 1, 2, 3, ... .) Intersects at one point P _{C at} an equal angle d ₂ as shown in FIG. 4 (B). Therefore, in such a case, data specifying the first intersection line CV1 and the point P _C (x _C , y _C ), the angle d ₂ formed by two adjacent intersection lines, and the angle a indicating the cutting range. Enter. Actually, the command shown below is CV1 ＝ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ； GROUP, 2, x _C , y _C , d ₂ , a, i ；. Here, GROUP, 2 indicates that it is a cutting passage pattern of the type shown in FIG. 4 (B).

Furthermore, when each cross section is a cylindrical shape that is perpendicular to the XY plane and concentric with each other, and the interval between adjacent cross sections is constant, the line of intersection CVi (i = 1) between each cross section and the XY plane is , 2,
3, ...) are concentric arcs as shown in FIG. 4 (C). Therefore, in such a case, the first intersection line CV1
The data for specifying, the distance d ₃ between two intersecting lines adjacent to each other, and the maximum arc radius dr that is the cutting range are input. Actually, the command shown below is CV1 ＝ ・ ・ ・ ・ ・ ・ ； GROUP, 3, dr, d ₃ , i ；. Here, GROUP, 3 indicates that it is a cutting passage pattern of the type shown in FIG. 4 (C).

In the example of FIG. 1, the cutting passage pattern shown in FIG. 4 (B) is specified for the curved surface 11, and the cutting passage pattern shown in FIG. 4 (A) is specified for the curved surface 12.

(c) When the specification of the cutting path pattern is completed, then the cutting order of the curved surface is input by the COMP statement and the CUT statement.

In the example of Fig. 1, the cutting order is entered by COMP, SS2; CUT, SS1 ;. The curved surface specified by the CUT sentence is the main curved surface (SS1), and the curved surface specified by the COPMP sentence is the sub curved surface (SS2). And
In the part where the curved surfaces overlap, the main curved surface has priority over the sub curved surface in the cutting passage pattern, and between the sub curved surfaces, the curved surface having the earlier cutting order has priority.

(d) When necessary data is input, the processor first generates each curved surface 11, 12 by a known method.

As shown in FIG. 5, j on the curved reference curve BSC1
The intermediate section curve including the th division point is expressed as L _c (j), and each intermediate section curve L _c (j) (j = 1, 2, 3, ...
.. L) is a curve formed by connecting the i-th division points of n)
When expressed as _r (i), the curves L _c (j) and L _c (j +
A quadrangle surrounded by 1), L _r (i), and L _r (i + 1) is called a patch PT (i, j). And the patch PT
The four vertices Q ₁ , Q ₂ , Q ₃ , and Q ₄ of (i, j) are created by the curved surface generation process, and the curved surface storage memory 10
6 is stored.

When the generation processing of each curved surface is completed by the above step (d), the following NC data generation processing is started.

(e) First, 1 → i and 1 → j.

(f) Next, the processor 102 obtains the intersection line CVi on the ith XY plane of the jth curved surface SSj given in step (b).

(g) If the i-th intersection line CVi is obtained, the processor 10
2 discretely obtains points on the cross-section curve when the j-th curved surface is cut by the cross section perpendicular to the XY plane with the CVi as the intersecting line.

That is, the processor intersects the intersections P _1i , P where the sides of the projection patch obtained by projecting each patch (see FIG. 5) on the j-th curved surface on the XY plane and the ith intersection line CVi intersect.
The coordinate value of _2i (see FIG. 6) is calculated. Then, the coordinate value of the point on the j-th curved surface corresponding to the intersection is calculated. That is, the coordinate value of each point on the j-th curved surface with each intersection point P _1i and P _2i as a projection point on the XY plane is obtained.

FIG. 6 is an explanatory diagram of a method for calculating the coordinate value of a point on a curved surface. Four sides i _a , i _b , j _a , j formed by projecting a predetermined patch P (m, n) on the three-dimensional curved surface on the XY plane.
Let P _1i and P _2i be the intersections between the predetermined two sides of _b and the i-th intersection line CVi, and have their coordinate values (x _1i , y
_1i), (x _2i, and _{y 2i),} further _Q 1 the end point of the side _{i a} the line of intersection CVi has crossover _{', Q} 2', the end points of the side _{i b} and _Q 3 ', _{Q 4',} the point Q _If the point on the three-dimensional curved surface corresponding to _i ′ (i = 1 to 4) is Q _i (i = 1 to 4) and the coordinate value of each point Q _i is (x _i , y _i , z _i ), ,
The Z-axis coordinate values z _1i and z _2i of the points P _1i ′ and P _2i ′ on the curved surface corresponding to the intersection points P _1i and P _2i are expressed by the following equation z _1i = z ₁ + (z ₂ −z ₁ ) (x _{1i -x 1) / (x 2} -x 1) z 2i = z 3 + (z 4 -z 3) is calculated by _{(x 2i -x 3) / (} x 4 -x 3). Then, (x _1i , y _1i ,
z _1i ) and (x _2i , y _2i , z _2i ) are the coordinate values of the points on the curved surface.

(h) Every time the point on the j-th curved surface is obtained, the processor checks whether or not the point is an intersection (boundary point) with another curved surface (referred to as the j'-th curved surface). The first point below the j'th curved surface is the intersection (boundary point). Therefore, the point on each curved surface corresponding to the projection point in step (g) is obtained, and it is checked whether or not the intersection is reached depending on the magnitude of the Z value.

(i) If the intersection has not been reached, it is checked whether the cutting direction boundary point of the j-th curved surface has been reached.

If the cutting direction boundary point has not been reached, the processing from step (g) is repeated.

(j) However, if the boundary point in the cutting direction is reached, check whether it has reached the boundary point in the feed direction.

(k) If the boundary point in the feed direction is reached, the curved surface generation processing ends, and thereafter, the processor creates NC data so that the tool sequentially follows the determined points, and the NC data creation processing is completed.

(l) However, if the end point in the feed direction has not been reached in step (j), the processing from step (f) onwards is performed for the next intersection line picked and fed by a predetermined amount in the feed direction as i + 1 → i, 1 → j. repeat.

(m) On the other hand, the point obtained in step (g) is the step
If it is found in (h) that it is an intersection (boundary point) with the j'th curved surface, the processor sets j '→ j.

(n) Next, the processor passes the intersection and intersects the intersection line CV _i parallel to the intersection line CV ₁ set corresponding to the j-th curved surface.
Is obtained, and the processing from step (g) is repeated.

<Effects of the Invention> As described above, according to the present invention, the tool can be moved along the cutting path pattern that matches the shape of each curved surface forming the compound curved surface, and the machined surface can be beautifully finished.

[Brief description of drawings]

 1 is a schematic explanatory view of the present invention, FIG. 2 is a block diagram of an apparatus for carrying out the present invention, FIG. 3 is a process flow chart of the present invention, FIG. 4 is a cutting passage pattern explanatory view, FIG. FIG. 6 is a diagram for calculating points on a curved surface, and FIG. 7 is a diagram for explaining a conventional method. 10 ... Compound curved surface, 11, 12 ... Curved surface that constitutes compound curved surface, 13 ... Boundary line of curved surfaces 11 and 12, 21 ... Radial cutting passage pattern, 22 ... Parallel straight line group cutting passage pattern

Claims (1)

[Claims] 1. A method for creating NC data of a compound curved surface, which is a composite of at least two three-dimensional curved surfaces, wherein data for specifying each curved surface and data for specifying a cutting path pattern of each curved surface are input, Obtain points discretely from the cutting start point of one curved surface to the boundary point with another curved surface along the cutting passage pattern set for that curved surface, and then follow the cutting passage pattern specified for the other curved surface. NC for discretely obtaining points on the other curved surface and tracing each point continuously to generate a compound curved surface
A method for creating NC data of a compound curved surface, characterized by creating data.